A recently named armored dinosaur, Denversaurus is based on a badly crushed skull from South Dakota. No other parts of the skeleton have been found, so it is difficult to estimate how long or heavy the animal was.

Denversaurus, along with Ankylosaurus, was found in the lower part of the Hell Creek Formation. Tyrannosaurus and Triceratops were also found in this formation. But unlike these animals, both ankylosaurs were only in the lower part of the formation. This suggests that some ankylosaurs became extinct long before the end of the Cretaceous. It is not known what caused their extinction, but it seems to be at the same time a number of other dinosaurs became less abundant.

The skull of Denversaurus is very large, and fusion (joining) of the bones may mean it was very old. It is possible that Denversaurus is actually an old nodosaurid ankylosaur Edmontonia. Few paleontologists believe Denversaurus is a valid genus.

Albertosaurus was an older "cousin" to the better-known Tyrannosaurus. In many ways the two were similar: the head was large compared to the body, the tiny forearms had only two fingers each is and the long tail balanced the body over two powerful back legs.Find out more about the Late Cretaceous dinosaurs.

Pinacosaurus was one of the first armored dinosaurs found in Asia. An expedition from the American Museum of Natural History went to Mongolia to search for traces of early man; instead they found dinosaur eggs and skeletons.